\input pstricks.tex
\input pst-node.tex
\nopagenumbers
$
\psset{linewidth=0.8pt,labelsep=0.5ex,unit=2em}
\pcline(0,0)(1.66,2.5)
\Aput{a}
\pcline(1.66,2.5)(4.66,2.5)
\pcline(4.66,2.5)(3,0)
\pcline(3,0)(0,0)
\Aput{b}
\psset{linewidth=0.4pt,labelsep=1ex}
\psarc{<->}(0,0){0.6}{0}{56.44}
\pcline[linestyle=dashed](1.66,2.5)(3,0)
\uput[l](2.33,1.7){d_1}
\pcline[linestyle=dashed](0,0)(4.66,2.5)
\uput[r](2.5,1.3){d_2}
\psset{framesep=1pt}
\uput{0.6}[30](0,0){\psframebox*{\varphi}}
\pcline{|<->|}(5.5,0)(5.5,2.5)
\ncput*{h}
$
\bye
